Key Characteristics of Essential Tremor
Essential tremor is a progressive neurological syndrome characterized primarily by bilateral action tremor of the arms and hands, with a frequency of 4-8 Hz, that significantly interferes with functional activities like writing, eating, and drinking. 1, 2
Core Clinical Features
Tremor Characteristics
- Bilateral, largely symmetric postural or kinetic tremor involving hands and forearms that is visible and persistent 1, 3
- Tremor frequency ranges between 4-8 Hz 2
- Action tremor is the hallmark—tremor occurs during voluntary movement and maintaining posture 1, 3
- Intentional tremor (worsening with goal-directed movements) and even rest tremor may occur in some patients 4
- Duration typically exceeds 3-5 years for diagnosis 2, 3
Distribution Beyond Hands
- Additional tremor sites include head, voice, legs, feet, trunk, jaw, chin, and tongue 4
- Isolated head and voice tremor without limb involvement argues against essential tremor diagnosis 2, 3
- Task- and position-dependent tremor should be absent for diagnosis 3
Exacerbating Factors
- Tremor worsens with emotional stress, caffeine consumption, and physical exertion 2
- Alcohol may temporarily improve tremor in many patients 5, 6
Associated Features Beyond Tremor
Motor Abnormalities
- Gait ataxia and postural instability 4
- Eye-motion abnormalities 4
- Dysarthria (speech difficulties) 4
- Cogwheel phenomenon may be present on examination 4
Non-Motor Features
- Cognitive disturbances including memory problems, executive dysfunction, and dementia 4
- Psychiatric symptoms such as anxiety, depression, and social phobia 4
- Sensory abnormalities including olfactory deficits and hearing loss 4
Functional Impact and Severity
Essential tremor can cause greater impairment than Parkinson's disease in activities like writing, eating, drinking, and reading 1
Severity Classification
- Mild: minimal interference with daily activities 2
- Moderate: some interference with daily activities 2
- Severe: significant interference with daily activities 2
The disorder significantly interferes with quality of life, functional activities, mood, and socialization, often forcing patients to change jobs or seek early retirement 1, 7
Diagnostic Requirements
Essential Criteria
- Bilateral action tremor present for at least 3 years 2, 3
- Absence of isolated head and voice tremor 2, 3
- Absence of task- and position-dependent tremor 3
- Consciousness remains intact during tremor episodes 2
Exclusionary Criteria
Must exclude: cerebrovascular disease, demyelinating disease, metabolic disorders, brain trauma, and psychological disorders 2
Red Flags Against Essential Tremor
- Duration of attacks greater than 1 minute 2
- Age of onset over 20 years 2
- Abnormalities in brain CT/MRI scanning 2
Epidemiology
Prevalence in the US ranges between 0.3% and 5.55%, making it the most common pathological tremor disorder 1, 5, 7
Progressive Nature
Essential tremor is a chronic, progressive syndrome with symptoms typically worsening over time 1, 3, 7